body {
  font-family: -apple-system, Segoe UI, Roboto, sans-serif;
  background: #0f172a;
  color: #e2e8f0;
  margin: 0;
}
header {
  background: #1e293b;
  padding: 1.5rem 2rem;
  border-bottom: 1px solid #334155;
}
header h1 { margin: 0; color: #38bdf8; }
header p { margin: 0.25rem 0 0; color: #94a3b8; }
main { padding: 2rem; max-width: 720px; margin: 0 auto; }
section {
  background: #1e293b;
  border: 1px solid #334155;
  border-radius: 8px;
  padding: 1.25rem 1.5rem;
}
input {
  width: 60%;
  padding: 0.5rem;
  border-radius: 4px;
  border: 1px solid #334155;
  background: #0f172a;
  color: #e2e8f0;
}
button {
  padding: 0.5rem 1rem;
  border: none;
  border-radius: 4px;
  background: #38bdf8;
  color: #0f172a;
  font-weight: 600;
  cursor: pointer;
}
pre {
  background: #0f172a;
  padding: 1rem;
  border-radius: 6px;
  margin-top: 1rem;
  overflow-x: auto;
  white-space: pre-wrap;
  word-break: break-word;
}
footer { margin-top: 1.5rem; color: #64748b; font-size: 0.85rem; }